SYDNEY (AFP) - Police on Monday were attempting to retrieve the body of a British tourist who slipped over the edge of a waterfall in Australia's Blue Mountains and plunged to his death.

The 20-year-old man was walking with friends at Wentworth Falls, west of Sydney, on Sunday afternoon when he lost his footing and fell some 80 metres.

Police said a friend summoned help and while paramedics were able to establish that he was dead, their helicopter crew was unable to retrieve the body due to high winds.

A guard was placed at the scene overnight and officers walked into the bushland on Monday morning to help winch him out.

A witness told state broadcaster ABC that she had seen a group of friends gathered on some rocks.

"Then they went down to the next one and I knew something was going to happen," she said.

"We just saw them all panic and a 20-year-old boy fell over, down the waterfall."

The Blue Mountains are a popular tourist attraction some 60 kilometres west of Sydney. Consisting mainly of a sandstone plateau, the area is dissected by gorges up to 760 metres deep.